Fibers of the Lyocell genus are produced by a solvent-spinning process, wherein the cellulose is dissolved directly in an aqueous tertiary amine-oxide without the formation of a derivative, and the solution is spun. Such fibers are also referred to as “solvent-spun” fibers. “Lyocell” is the generic name allocated by BISFA (The International Bureau for the Standardization of man made fibers) for cellulose fibers which are produced by dissolving cellulose in an organic solvent without the formation of a derivative and extruding fibers from said solution by means of a dry-wet spinning process or a melt-blown process. In this regard, an organic solvent is understood to be a mixture of an organic chemical and water. At present, N-methyl-morpholine-N-oxide (NMMO) is used as an organic solvent on a commercial scale.
In said process, the solution of the cellulose is usually extruded by means of a forming tool, whereby it is moulded. Via an air gap, the moulded solution gets into a precipitation bath, where the moulded body is obtained by precipitating the solution. The moulded body is washed and optionally dried after further treatment steps. A process for the production of Lyocell fibers is described, for instance, in U.S. Pat. No. 4,246,221. Lyocell fibers are distinguished by a high tensile strength, a high wet-modulus and a high loop strength.
It is well-known to modify cellulosic fibers and also Lyocell fibers via the incorporation of various additives.
In this respect, EP 1 259 564 B1 discloses Lyocell fibers which contain a material of sea plants or shells of sea animals. As sea plants, mussels are mentioned amongst others. Shells of mussles, however, contain all the contaminations that are deposited on the outer side of the shell, i.e. the side being in contact with the water.
CN 1772980 A discloses a viscose fiber containing pearl powder.
Also CN 1450212 A discloses fibers containing pearl powder. However, the fibers mentioned in CN 1450212 A are non-cellulosic synthetic fibers.
Pearl powder (i.e. ground pearls) is well-known since long time from Chinese medicine as health- and beauty-promoting and, therefore, is used in cosmetic products. This material mainly consists of CaCO3 and of proteins.
The manufacturing processes for making viscose fibers and, especially, making non-cellulosic synthetic fibers differ significantly from the manufacturing process for making Lyocell fibers. Especially, in the viscose process various substances that are detrimental to the environment must be used for the production of the spinning solution. Furthermore, the manufacturing processes of these fiber types are carried out at conditions that are detrimental to the components of the pearl powder and, therefore, reduce the yield and worsen the properties of the product, respectively. Incorporating pearl powder into non-cellulosic synthetic fibers results in a low bioavailability of the powder, because the powder is encased within the fibers and, due to the hydrophobicity of such fibers, only a limited exchange with the environment is possible. In the viscose process, on the other hand, the precipitation of the fibers in an acid precipitation bath containing H2SO4 damages the CaCO3 contained in the pearl powder. In any event, the CaCO3 is partly dissolved, and also one must expect partial precipitation in the form of CaSO4.
Furthermore, the properties of the various fiber types differ significantly from each other.
It is an object of the present invention to provide a fiber in which pure pearl material is present with a high bioavailability and wherein said fiber can be produced with a process that preserves the pearl material as much as possible.